Jeff Steinberg had a maroon and white lacrosse jersey that he wore for years. It said "Denver Lacrosse" on the front and had his number, 5, on the back.

Then, one day, he cleaned out his closet and took the shirt to a Goodwill store in Miami. He figured that was the end of it. But some months after that, Steinberg found himself in Sierra Leone for work. He was walking down the street, and he saw a guy selling ice cream and cold drinks, wearing a Denver Lacrosse jersey.

"I thought, 'Wow, this is pretty crazy,' " Steinberg says. Then he looked at the back of the shirt — and saw the number 5. His number. Steinberg tried to talk to the guy about the shirt, but he didn't speak much English and they couldn't really communicate.

A Kenyan importer of T-shirts waits for vendors to come and buy his bales. Importers will not open the bales for vendors to inspect, passing on the risk of poorly sorted clothes or sizes to the vendors.

Customers scramble to grab T-shirts as a bale is opened at Gikombo Market. Some people are shopping for themselves, while others will wash, mend and iron the clothes and sell them for a higher price to earn a living.

Sarah Elliott for NPR

A T-shirt vendor at Gikombo Market wears a shirt he bought from the market.

Sarah Elliott for NPR

After T-shirts are purchased out of the bales in Gikombo Market, they are washed, mended and ironed. Men use coal irons to press clothes to be resold for a higher price.

Sarah Elliott for NPR

A tailor shop above Gikombo Market handles repairs and alterations of T-shirts and clothes from the market. Scissors and a mobile phone are tied down next to a sewing machine at the shop.

Sarah Elliott for NPR

Customers bring T-shirts to tailors to have them mended or resized to then sell for a higher price in the market or elsewhere.

Sarah Elliott for NPR

Vendors at Gikombo Market wait for customers to buy their clothes.

Sarah Elliott for NPR

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"I spent a lot of time thinking about that over the following days," Steinberg says. "It was just beyond me how it could have gotten there."

It turns out the epic voyage of Steinberg's jersey — from a used clothes bin in the U.S. to sub-Saharan Africa — is actually really common. Lots of U.S. shirts (including, it seems safe to say, lots of Planet Money T-shirts) will eventually make the trip.

Charities like Goodwill sell or give away some of the used clothes they get. But a lot of the clothes get sold, packed in bales and sent across the ocean in a container ship. The U.S. exports over a billion pounds of used clothing every year — and much of that winds up in used clothing markets in sub-Saharan Africa.

We recently visited the giant Gikombo Market in central Nairobi. There's a whole section for denim, and another for bras. We, of course, headed for the street of T-shirts, where vendors lay out their wares on horse carts. The shirts have been washed, ironed and carefully folded. It's more like Gap than Goodwill — if Gap had a very strange product line.

Just to pick at random from one cart: There's a fundraising T-shirt for a cancer charity, a shirt from a weightlifting competition in southern Montana and a shirt marking "Jennifer's Bat Mitzvah" in November 1993.

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Margaret Wanjiku, a T-shirt vendor from western Kenya, has come to this market to restock her supply. What's written on the T-shirt is often not that important to her customers, she says. She's looking more at the condition of the shirt — the "smartness."

Like many vendors here, Wanjiku stays away from shirts that are extra-large, because those are too big for almost all of her customers. But there is at least one guy in Nairobi looking for extra-large shirts.

Francis Mungai cuts up XL shirts with scissors and, working with a seamstress, turns them into slimmer, smaller shirts.

One recent day he bought an extra-large Motorhead shirt and, in a few minutes, turned it into a slim, custom shirt with a blue collar and canary-yellow sleeves. The Motorhead shirt was imported to Kenya for 15 cents. It was resold and sold again for 45 cents. Then someone got 12 cents to cut it up, 18 cents to tailor it and 14 cents to wash and iron the shirt. Then a vendor bought it for $1.20, with plans to sell it for $2 to $3.

Update: A caption in the slideshow incorrectly referred to a shirt as a Tupac shirt. Thanks to the commenter who pointed it out.

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